1. Field of the Invention
The invention is directed to a power semiconductor module used in a pressure contact embodiment, with controllable power semiconductor components.
2. Description of the Related Art
In the prior art, such as German Patent Application No. DE 197 19 703 A1, power semiconductor modules comprise a housing with at least one electrically insulating substrate disposed therein, preferably for direct mounting on a cooling component. The substrate in turn comprises an insulation body having a plurality of metal connection tracks located thereon and insulated from one another, and power semiconductor components located thereon and connected to the connection tracks. Moreover, known power semiconductor modules have load terminals for connecting to an external load as well as auxiliary terminals, and also have connecting elements located in the interior of the module. These connecting elements for connections in the interior of the power semiconductor module are usually embodied as wire bond connections.
Pressure-contacted power semiconductor modules are also known, of the kind disclosed in German Patent Applications Nos. DE 42 37 632 A1 and DE 199 03 875 A1, or in German Patent No. DE 101 27 947 C1. In the first of these references, the pressure device has a stable, preferably metal, pressure element for pressure buildup, an elastic pad element for pressure storage, and a bridge element for introducing pressure to separate regions of the substrate surface. The bridge element is preferably designed as a plastic molded body with a face oriented toward the pad element, from which face many pressure prongs emanate in the direction of the surface of the substrate.
By means of this kind of pressure device, the substrate is pressed against a cooling component, and the heat transfer between the substrate and the cooling component is thus permanently assured. The elastic pad element maintains constant pressure conditions under various thermal loads and over the entire service life of the power semiconductor module.
German Patent Application No. DE 199 03 875 A1 develops this known pressure element further such that on the one hand it has an especially advantageous ratio of weight to stability, and, on the other, it has electrically insulated openings for permitting the passage therethrough of conductive elements. To that end, the pressure element is formed as a plastic molded body with a metal core on the inside. This metal core has recesses for the passage of terminals, preferably auxiliary terminals in a spring contact embodiment. The plastic molded body surrounds these recesses in such a way that the auxiliary terminals are electrically insulated from the metal core by the plastic molded body.
Further-developed pressure elements are also known which have many pressure prongs on their surface oriented toward the substrate. Preferably, the metal core also has a pre-set sag. When the two provisions are combined, a pressure element of this kind can furnish the entire functionality of an aforementioned pressure device.
German Patent No. DE 101 57 947 C1 discloses a power semiconductor module in which the load terminals are embodied such that they extend in portions closely adjacent to and perpendicular to the substrate surface and have contact feet extending therefrom that furnish the electrical contact with the conductor tracks, while also exerting pressure on the substrate, and thereby establish its thermal contact with a cooling component. The pressure is introduced and stored using means of the prior art.
German Patent Application No. DE 10 2004 021 927 A1 describes a method for internally insulating power semiconductor modules. In contrast to the previously known prior art, they are not filled with an insulating silicone gel up to a defined fill level. Rather, this patent discloses a method for coating the components and connecting elements to be insulated which is quite economical in terms of the amount of silicone gel needed.